Portable objects of the above kind that are provided with electrical connection means between an electronic circuit in the case of the object and an antenna in the wristband have already been described in the prior art.
European Patent No. 0 631 341 describes a wristwatch type electronic instrument including an antenna accommodated in the wristband and connected to an electronic circuit for processing signals received via the antenna. The processing electronic circuit is on a printed circuit board inside the case of the instrument. Connection lands are provided on an edge region of the printed circuit board for making an electrical connection between the electronic circuit for processing signals and the connection terminals of the antenna, which pass through a lateral wall of the case. In a first embodiment, fixing screws pass through appropriate openings in the antenna terminals and screw directly into the printed circuit board at the location of the connection lands to make the electrical connection.
A second embodiment uses a leaf-spring connection for each terminal of the antenna that is fixed to the printed circuit board and on which an electrical conductor connected to one of the terminals of the antenna presses. Each conductor connected to a terminal of the antenna must pass through the lateral wall in order to press on the leaf-spring to make electrical contact. An O-ring is provided around said conductor where it passes through the lateral wall.
A drawback of the electronic instrument described in European Patent No. 0 631 341 is that a portion of the antenna has to pass through a lateral wall of the case in order to be connected directly to the printed circuit board. Because of this, and because of manipulations of the wristband, a permanent seal at the lateral wall of the case cannot be guaranteed, even using an O-ring.
Another drawback of the first embodiment using fixing screws is that subsequent replacement of the antenna in the event of a problem makes it essential to demount the case of the instrument completely before obtaining access to the fixing screws, which may make this operation tiresome.
Another drawback of the second embodiment using a leaf-spring is that the spring is typically soldered to the printed circuit. This must be done carefully to guarantee sufficient mechanical strength in relation to perpendicular stresses exerted on the spring when the electrical conductor presses on it. It may further be noted that the contact surfaces between the blade and the electrical conductor are not protected, which may lead to problems with the stability of the electrical connection, in particular because of possible oxidation of the exposed metal surfaces. What is more, this solution is relatively bulky and consequently is not suitable for producing a compact instrument.
U.S. Pat. No. 5,168,281 describes an antenna connection device for electronic equipment such as a wristwatch. An antenna end housed in one portion of the wristband is firmly fixed to an electrical conductor. This conductor passes through a lateral wall of the case to be connected to a contact blade of a printed circuit board carrying an electronic circuit. An O-ring is provided around the conductor where it passes through the lateral wall.
As in the previous document, a drawback of the solution proposed in U.S. Pat. No. 5,168,281 is that the antenna conductor has to pass through a lateral wall of the case in order to be connected to the contact blade on the printed circuit board. Because of this, and because of manipulations of the wristband, a permanent seal at the lateral wall of the case cannot be guaranteed, even using an O-ring.